Bovine ß-Lactoglobulin E, F and G of Bali (Banteng) Cattle, Bos (Bihos) Javanicus

Abstract

An electrophoretic examination is made of samples of milk from eight Bali (banteng) cattle, Bos (Bibos) javanicus, in the Northern Territory of Australia. There are two new electrophoretically distinct bovine ft-Iactoglobulins, designated E and F, present in these samples. It is shown by amino acid analysis and tryptic peptide mapping of isolated samples that: (I) both E and F differ from the B variant of domestic cattle (Bos taurus) by + 1 G1y, -1 Glu at residue 157 or 158; and (2) the F variant has the additional charge differences from E and B due to + I Tyr, -1 Asp at residue 129 or 130. It is also shown by studies of peptides produced by the action of Staphylococcus aureus strain V8 protease and by more recent amino acid analyses that (1) the GlyjGlu substitution is at residue 158; (2) there is an additional Bali variant, designated ft-lactoglobulin G, differing from E by + 1 Met, -1 lie at residue 78, but having the same mobility as E; and (3) there is an hitherto undetected neutral residue substitution of + 1 Ser, -1 Pro at position 50 in the F variant. The relation of these variants to other known ft-lactoglobulin variants of the Bos genus is discussed.